This invention relates to an area of electronic equipment assembling using packaged and unpackaged electronic components, and more particularly to a construction of a three-dimensional electronic module and a method of its fabrication and repair.
A known structural solution is disclosed in U.S. Pat. No. 3,725,744 HO5K 1/04 dated Nov. 6, 1971, "Connecting Assembly of Electronic Components".
An assembly for electric connection of different tiny electric components, one to another, comprises a flat surface, such as a motherboard, which holds the electric components, and at least one thin isolating ribbon, placed on a plane, disposed perpendicularly to the surface and having a plurality of apertures, disposed according to a preliminarily defined circuit pattern. A plurality of shared electroconductive pillars and at least one electroconductive bus are mounted on opposite sides of the isolating ribbon and are disposed transversally in order to pass through the apertures, according to the preliminarily defined pattern. In this case the selected beforehand pillars are welded to selected buses through the penetrated apertures and also are electrically connected to the different electric components according to the beforehand determined circuit pattern. It follows from the Patent description and FIG. 1, that the components are placed among the boards of modules, being parts of the assembly. Additionally the modules have electric contact with the motherboard through one of the board's side.
Advantages of this solution are the complex building the apparatus and obtaining a benefit from disposing the electronic components among the boards.
A shortcoming of this construction is a high labor-intensity of primary mounting electronic components and a complexity of extracting a failed component (it is necessary to unsolder a module and all the components at least from one board); also problems of heat removal are not solved.
Also known is a solution according to France Patent No. 1.487.033, dated May 22, 1967 for, "United Circuits Block and Method of Its Fabrication".
A packaged component is inserted into a flat board so, that its leads go to the board's grooves and end flush with the board's edge. The boards are assembled, forming three-dimensional module construction. Conductors, connecting components one to another, are deposited on borders of the module. The module is covered by a lid (at the top), and there is a board with external contacts at the bottom. All the boards are glued one to another, forming a monolithic construction.
This solution has all the advantages of three-dimensional assemblies, including allowing use of packaged components.
A shortcoming of this construction is the impossibility of dismounting it and the complexity of extracting a failed component. A problem of heat removal directly from a component is not solved.
A known technical solution is published in, "Reference Manual of Radio-Electronics Apparatus Designer", editor R. G. Varlamov, Moscow, "Sov.Radio", 1980), p.105, FIG. 5.4f.
Stacked modules having different heights are placed between parallel disposed commutation boards and have electrical and mechanical contact with them. The highest module determines the assembly's height while the rest of the modules have mechanical contact with one board and are electrically connected with the other board by leads with different lengths.
This solution is very schematic. In order to dismount and substitute for any failed module it is necessary to unsolder all modules from one of the boards. The again mounting of the board is also difficult, because it is necessary to insert simultaneously all module contacts into the unsoldered board. The problem of heat removal is not solved.
A known solution is described in A.C.SU 1167774 A HO5K 13/00 dated Jan. 21, 1983, "Method of Radioelements Mounting Between Adjacent Boards of Radio-Electronic Devices and Tool for Its Implementation".
According to this Author Certificate a method includes: disposing radioelements between mounting boards, shaping leads from one side of the radioelements and inserting the leads into mounting apertures of the boards (with preliminary shaping of the leads from one radioelement side being accomplished by bending them at right angles to a lead axis). During insertion of the leads into the mounting apertures of the boards the radioelements are disposed between the boards, shifted to one of the boards while inserting non-shaped radioelement leads into mounting apertures, the pre-shaped leads of the radioelement are unbent and the radio elements are shifted to the other board while inserting the unbent leads into the board's mounting apertures. A tool for mounting the radioelements between adjacent boards is a fork, formed by two pivots, mounted with a gap at a handle; additionally the pivots have flat surfaces, turned one to another, and a side surface of one of the pivots is conjugate with its flat surface by means of a cylindrical surface with variable curvature.
An advantage of this technical solution is the possibility of substituting a packaged component, disposed between two parallel hard commutation boards without dismounting the rest of the components of the module, and also of developing one of the repair tool constructions.
But there is neither a constructive solution of a three-dimensional module with components disposed between the boards, nor a sequence of module fabrication operations and constructive solutions concerning heat removal from heat emitting components, which significantly limits areas in which the invention can be applied.
A construction is known of an electronic devices package according to German Patent DE 3813396 A1 HO5K 5/02 dated Nov. 2, 1989. The package of electronic devices proposed, is characterized such that at least one wall of a device is a metal connecting plate, providing high mechanical strength and optimum heat removal.
An advantage of this construction is that it provides strength and heat removal from the electronic device.
Shortcomings of this invention include an absence of whole module construction and of module assembling and repair sequences.
A technical solution is also known according to U.S. Pat. No. 5,025,307 HO1L 39/02, dated Jun. 18, 1991, "Modular Semiconductor Device".
The modular semiconductor device comprises, as a rule, a couple of parallel circuit boards and a plurality of IC packages, mounted between the electronic circuit boards. Two or more modular semiconductor devices can be assembled, one on the other, so that a memory capacity can be easily increased, and a functional level can easily be raised. A heat emitting rib having a planar or comb structure can be provided in close contact with the IC package.
Advantages of this construction are obtained from disposing IC packages between circuit boards and also from the proposed variant of the heat sink comb construction. But variants of primary assembly of the modular device can be a very labor-consuming, and also possibilities of its repair are not disclosed in the Patent. Applying a gas as a cooling element makes the construction bulky and, practically, doesn't give any benefit in volume in comparison with conventional mounting methods.
A module's construction with a heat conductive wall is known according the U.S. Pat. No. 3,348,101, dated Oct. 17, 1967.
This is a high density module, comprising a heat conductive wall, including a rectangular flat plate having good heat conductivity and essentially straight edges, with assembling projections fastened along each of parallel edges of the flat plate. There are two printed circuit boards, each of them being mounted over one of the assembling projections and being flat-parallel to another board, the boards having printed circuits at least on one side and including notched edges. A plurality of electric components with leads, are mounted into the notched edges of the printed circuit boards, and the wall comprises an aperture and a flange for mounting an additional electric component, providing means for heat removal from this component.
Advantages of this construction include the possibility of applying different electronic components with comparatively simple primary assembly and repair and also a solving of the problem of heat removal from heat emitting components by placing them in the apertures of the heat removing fin.
A significant limitation is that component contacts are disposed only in one row at each side of heat conductive fin. This brings into doubt a soldering of component leads into the boards notches, from a reliability point of view. A general construction of the module for electronic devices arranging is not shown.
The closest solution to the invention of this patent application is that according the Author Certificate SU 1167774 A.
It is an object of this invention to create a universal construction of a three-dimensional electronic module with a possibility to apply packaged and unpackaged components, providing at the same time high packing density and effective heat removal and also maintaining a good reparability.